Ultralow birefringence measurement in optical fibers by use of a fiber optical loop mirror

Summary form only given. Most experimental techniques proposed to measure fiber birefringence use a section of a fiber with a length of several beat lengths. These techniques are convenient for high-birefringent fibers, but it is difficult to use them for low-birefringent fibers. We show for the first time that a Fiber Optical Loop Mirror (FOLM) composed of a coupler with output ports connected by the fiber to be measured provides a very simple and accurate measurement of the birefringence of low-birefringent fibers.